ERG mode elite direto problems

I have just brought a new elite direto trainer, I like doing the workouts on zwift and after trying to do a session I have found ERG mode doesn’t work very well with the trainer and the wattages don’t stablise on the set interval like I had on my old on wheel trainer. I connected via Bluetooth and have just brought and used an ant + usb and still having the same issues holding the set wattage for a workout interval. I have calibrated etc and no luck.

Any advice?